• Central DI
• Nephrogenic DI
• Osmotic Diuresis (in DM)
• Excessive water intake

Definition: more than 3 L U/O - Urine output (0.5-1 cc/kg/h) a day

• Can be a symptom of
  • ↑ Hyperglycemia (> 7) (Diabetes Mellitus )
  • DI - Diabetes Insipidus
• If input = output, will also have Nocturia

Approach to Polyuria

1. Is the patient REALLY experiencing polyuria, or is it an increase in urine frequency?
   1. Confirm 3L urine a day
2. If the patient drinks a lot of water, why?
   1. Psychogenic Polydipsia or Health belief
   2. Reduce fluid intake and see if the urine output drops
3. Investigate causes of polyuria
   1. Osmotic diuresis
      • Diabetes Mellitus : A symptom of ↑ Hyperglycemia (> 7) (when glucose > 12-15)
   2. Water diuresis
      • Psychosis
      • DI - Diabetes Insipidus: high urine output drives the drinking
        • Central DI → pituatory
        • Nephrogenic DI → Li, Ca↑, K↓
   3. Iatrogenic
      1. Diuretics use
      2. Hospitalization
         • Mannitol
         • Urea content in TPN
         • Excessive IV Fluid Resuscitation
   4. Renal AKI
      • Salt-wasting nephropathy